Marketing people have spent millions convincing people that natural stuff is great and good for you while chemicals are bad and hazardous. Same with organic products. The fact that they convince people to buy these products and likely pay a premium is proof of their effectiveness.
There are many natural items that will kill (cyanide is a simple natural substance present in many stone fruit pits–three crushed cherry pits contain enough cyanide to kill a person) or cause cancer. While many point out that the cancer causing elements of tobacco are due to burning it and inhaling deeply, this is only partially true. People using smokeless tobacco are known to be at higher risk of mouth cancers–so at least some of the carcinogenic compounds are naturally occurring in the unburnt leaf.
TL/DR–Natural does not mean safe or healthy.
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